Spontaneous - I think being upfront opens more discussion for you to be upcharge but I’m also prepared for whatever happens meaning getting more from what you paid for or what was just advertised. As for tipping, almost never but I do tip my servers in the restaurant or bar (it’s, an incall, you drove there, find a parking then drive back home lol that’s too much to tip them - plus you also pay them in cash) IMO ?